Process for the manufacture of benzene, toluene, and other aromatic hydrocarbons and the like



W. F. RITTMAN. PROCESS FOR THE MANUFACTURE OF BENZENE, TOLUENE, AND OTHER AROMATIC HY'DROCARBONS' RENEWED DEC. l8. I917.

Patented June 6, 1922.

mv'en%07w Attorney names were FTENT FFHQQY WALTER F. RITTMAN, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR T0 SYNTHETIC HYDRO-CARBON COMPANY, OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF DELAWARE.

PROCESS FOR THE MANUFACTURE OF BENZENE, TOLUENE, AND OTHER AROMATIC HYDROCARBONS AND THE LIKE.

Application filed May 18, 1915, Serial No. 29,019.

T 0 all w 71 0 m it may concern.

Be it known that I, IVALTER FQRITTMAN, residing at Pittsburgh, in the county of Allegheny and the State of Pennsylvania, have invented or discovered certain new and useful Improvements in Processes for the Manufacture of Benzene, Toluene, and Other Aromatic Hydrocarbons and the like, of which the following is a specification.

The invention described herein relates to a process for the manufacture of benzene, toluene and other aromatic hydrocarbons and the like and has'for its object the manufacture or conversion of such products either from crude mineral oils or from the products thereof, or from liquid hydrocarbons or liquid hydrocarbon products obtained from bitumen, shale, coal, lignite, peat, or other substances capable of yielding liquid hydrocarbon products.

The process described and claimed herein is not only well adapted tothe-recovery of benzene and toluene from the materials above mentioned in which these constituents naturally occur; but also is particularly applicable to the production or creation of benzene, toluene, and other aromatic hydrocarbons and the like from practically any liquid hydrocarbon product; including those mineral oils or the products thereof having a distinctly parafiine base, in which it has been found that practically no benzene or tolu-- ene exist. Theparticular process for producing benzene and toluene from xylene, cymene, etc., is described in my copending applicationser. No. 38,461, filed July 7, 1915.

It is characteristic-of my improved method that cracking is effected after the material has been gasified. The material is transformed from a liquid to a gaseous form and then subjected to temperatures at which the gaseous material will be cracked, permitting ofthe formation of new combinations, the formation of such new combinations being promoted by maintaining the gases under a suitable pressure.

In the practice of my invention the heavy material is continuously fed into a highly heated zone formed by asuitable receptacle in which suitable provision is made whereby the material is transformed into a gaseous condition. The gases are passed immedi- Specification of Letters Patent. patgntd J 5 1922 Renewed December 18, 1917. Serial 150.207,?94.

ately into a zone in which it is preferred to maintain a temperature higher than that in the gaslfying zone. While practice has shown that a temperature of approximately 600 degrees 0., more or less should be maintained in the gasifying zone and an equal, but preferably a much higher, temperature should be maintained in the second or cracking zone, it will be understood that the tained by maintaining temperatures ranging between 650 degrees C. and 800 degrees (1., more or less, in the respective zones.

In the cracking operation a large number of different products are formed, ranging from hydrogen to hydrocarbons having boiling points the same, or even higher, than those in the materials treated. The cracking permits of the formation of new and more volatile combinations. The maintenance of gases resulting from the cracking, such as hydrogen, methane, ethylene, ethane, etc., having boiling points below atmospheric temperature, and which will for the purposes of this case, be hereinafter termed permanent gases in the cracking zone, is an im portant feature of my improved process as will be hereinafter stated.

In order to promote the formation of the new combinations of hydrocarbons more volatile than the materials treated, pressure above atmospheric pressure should be maintained in the second zone.

It is well known that in chemical reaction there is a tendency to establish and maintain a state of equilibrium. "As, for example, in the cracking of the gaseous hydrocarbons as above described, two classes of gases are formed, i. e., those condensable at temperatures above atmospheric, and those which remain uncondensed at atmospheric temperature. such as the permanent gases referred to. If the condensable gases be withdrawn or removed, the cracking being continued, the other or permanent gases, being in the sphere of reaction there will be a tendency to restore the equilibrium and form the condensable hydrocarbons rather than those not condensable at atmospheric temperature. This tendency to form the condensable hydrocarbons will be prompted by high concentration or increase of the density of the permanent gases in the sphere of reaction. To this end, a pressure substantially above atmospheric pressure is maintained in the reacting zone. While the desired pressure can be produced in any suitable manner or by any. suitable means, it is preferred to obtain such pressure by controlling the discharge of the gases from the reaction zone. It will be understood that although the best results can be obtained by employing for a given material a certain temperature and a certain pressure, thesetwo are in*no Way interdependent. It is generally preferred to use high temperatures with high pressures, and the temperatures and pressures are generally those which cannot be obtained in a two phase system.

While the pressures employed will vary with the character of he material treated, the best results will be obtained by maintaining a pressure of about pounds and higher. in the generating zone, the efficiency of the process increasing as the pressure employed is increased. In combination with high temperatures it has been found that a pressure of about 60 pounds per square inch and upwards gives satisfactory yields.

It will be understood that in the practice of my invention, the conditions of opera-.

tion, i. e., temperature, pressure andtime, can be changed and adapted to produce a de siredproduct in greater quantity or a different character of product, or either or all of them at will. By reason of having the reaction occur substantially in the gaseous state, a flexibility in the application of the above conditions is permitted which is impossible in any distillation process, or in any other process involving the retention of liquids in the sphere of reaction. It is well known that in a two-phase system, such as occurs when both liquid and gas are present in the reacting zone, temperature and pressure are interdependent-one being fixed by the condition chosen for the other; whereas, in a singlephase system, such as occurs when the product to be treated is in the reacting zone in a gaseous condition, apart from the liquid. it is possible to exercise control over each one of the above stated conditions or variables,

selecting any temperature, and any pressure below the condensation pressure for that temperature and retaining the gases for any required time under the chosen conditions of operation. It is characteristic of my improved process, that by controlling the feed of the material to be generated into gases, or by regulating the flow of the converted gases into or from the zone of reaction, or by varying the length of the reaction zone, it is possible to regulate over wide limits, the time or duration of the reactions effected, and regulate at the same time the pressure and temperature at will, each independent of the other. It is impossible to do this in any two-phase system.

While not necessary, it is preferred that the gasification should be effected above the reaction or cracking zone, and that the condensable gases be removed at a point below the cracking zone, as advantage can be taken of the difference in the character or nature of the permanent and condensable gases, the former being the lighter and therefore having a tendency to remain in or to return to the reaction zone, as is desired in the practice of this process.

The shape and dimensions of the portion of the apparatus forming the reaction or cracking zone can be varied within wide limits, but provisions should be made for such relative movements of the gases as will promote the separation above referred to. or movements or subsidence of the condensable gases from the cracking Zone and a relatively slower subsidence of such permanent gases as may be carried along by the condensable gases as they move away from the cracking zone.

The temperature employed in the practice of my invention depends upon the character of the hydrocarbon material to be treated and the character of the product desired. But the temperature employed for gasifylng should be sufficiently high to insure the substantially instantaneous gasification of so much of the material as is capable of gasification under practical conditions. and the temperature in the cracking zone should be higher than that in the gasifying zone, and will depend in commercial operations largely upon the character of the material treated and the product desired.

By expanding the hydrocarbons in small quantities into gases and then subjecting these gases to high temperatures and high pressures, the speed of reaction incident to high temperatures is attained without incurring any great liability to blowouts.

It will be understood that in the operation of this invention, the three variable factors'time, temperature, and pressurecan each be varied independent of the other. By reason of this fact, it is possible to vary the quantity of a given product desired. by

suitably changing these factors: as for example, we can produce some benzene at a temperature preferably employed in the manufacture of gasoline by maintaining the material treated in a gaseous condition in the reaction zone for a comparatively longer appreciably larger quantities, and these time. But it is preferred to operate at higher temperatures, where benzene, toluene, and other aromatic hydrocarbons will form in quantities can be materially increased if the gases are held for a sufficient length of time sure of about 250 pounds per square inch and upwards.

For the purpose of illustration, I have shown in the accompanying drawing an exemplification of a simple form of apparatus adapted to the practice of this invent-ion, although it will be understood that the particular apparatus shown is but typical of many others having the same capabilities. It is also contemplated that any convenient and efiicient source of heat may be substituted for the electricity which I have used in the experimental apparatus.

Figure l is a side view of the apparatus, partly in section. Figure 2 illustrates a type of fractional condenser that may be used with this or any similar apparatus.

Referring to the drawing, A indicates a chamber or receptacle capable of withstanding the pressure and constitutes the hydrocarbon cracking zone. aisa resistance wire, properly insulated, in contact with A which is incased in a protective coating of asbestos or other material adapted to prevent excessive radiation of heat. I) and d are binding posts from which conductors lead to a proper source of electrical energy. 0 is a conducting rod through which one end of the resistance coil is connected to bind post (1. B is a rheostat used for controlling and regulating the current supplied. (2 is a branch tube opening into A through which the pyrometer couple is introduced whereby the temperature prevailing may be read from an appropriate instrument. f is a rod to support a perforated disc m which supports a quantity of filling material 9 introduced into the upper portion of A. This filling material may be metal balls or any other material which will serve as an efficient spreading surface for vaporizing the oil used, as well as a heat conductor and heat disseminator. It Will be understood that the use of this filling material is not indispensable to the operation of my invention as the gasification of the material being treated may be facilitated or accomplished by any other suitable means. C is a feed cup or receptacle for supplying oil to A above g. The pressure in the upper part of C is equalized with that in tube A through an equalizing connection. A may also be contransformed into gas.

nected with a suitable gauge for reading the pressure therein? D is a condenser which leads through a pipe H to a receptacle E for the collection of liquid distillates. F is a pipe and G a release valve through which the gaseous products evolved during the process may be permitted to escape into a gas holder not shown. In the form of apparatus shown in Fig. 1 a condenser D is cooled to a suflicient degree to condense allvapors. Condensate passes through H to a collecting vessel E from which said con densate may be withdrawn and fractionally distilled. In case a fractional condenser is desired the equipment shown in Fig. 2 would be put in place of E in Fig. 1 and the temperature of condenser D maintained so as to condense only the heavy hydrocarbons and permit the more volatile vapors to pass to a secondary condenser M to be collected in receptacle N.

With the type of apparatus above de scribed and shown in the accompanying drawing, proceed substantially as follows: The cracking or reacting chamber heated to the desired cracking temperature of the material by passing an electric current of appropriate wattage through the heating element (1. l/Vhen the tube A and the filling material 9 contained therein have attained the appropriate temperaturey the feed is opened and the material is permitted toenter the upper part of the tube A where it spreads over the filling material and is flashed or substantially instantaneously In the meantime the valve G has been closed in order to bring the concentration of permanent gases to the desired point. sure has been attained valve G can be opened from time to time to release excess pressure created in A. The hydrocarbon gases pass into the cracking zone of the tube A. After passing through the cracking zone, the hydrocarbon gases are condensed and collected in receptacle E, thereby being removed from the sphere of reaction.

' I claim: I

1. The process herein described which consists in feeding hydrocarbon fluid of the petroleum type to a substantially vertical unobstructed chamber subjecting such fluid to a vaporizing temperature at a point adjacent to the initial point of flow, subjecting the vapors while passing through the chamber to a temperature not less than 600 degrees G. and a pressure of 60 pounds per square inch and upwards and withdrawing After the desired pres-- the vapors continuously from the opposite hydrocarbon of the petroleum type to one end of a substantially vertical unobstructed chamber withdrawing the vapors from the chamber and subjecting the vapors While passing through the chamber to a temperature not less than 600 degrees C. and a pressure not less than 60 pounds per square inch and upwards, the conditions of pressure, temperature, and rate of flow being so adjusted. as to promote the formation of aromatic hydrocarbons.

3. The process as claimed in claim 2 which comprises condensing the benzene, toluene, and other aromatic hydrocarbons formed during the passage of the vapors through the chamber.

4. The process herein described which consists in causing a continuous flow of a substantially uniform mixture of vapors of hydrocarbon of the petroleum type through a substantially vertical unobstructed chamber, subjecting the vapors while passing through the chamber to a temperature not less than 600 degrees C. and a pressure of 60 pounds per square inch and upwards, the conditions of pressure, temperature, and rate of flow being so adjusted as to promote the formation of aromatic hydrocarbons.

5. The process as claimed in claim 2 in which the vaporized hydrocarbons are subjected to a temperature not less than 600 degrees C. and a pressure of 250 pounds and upwards.

6. The process herein described which comprises causing a continuous flow of vapors of hydrocarbon of the petroleum type through a substantially vertical unobstrucb ed chamber and subjecting the vapors While flowing through said chamber to a cracking temperature of the order represented by minimum and maximum temperatures of 650 and 800 C. and pressures of the order of 250 lbs. per square inch. the conditions of pressure, temperature, and rate of flow being so adjusted, as to promote the formation of aromatic hydrocarbons.

In testimony whereof, I have hereunto set my hand.

' WALTER F. RITTMAN. 

